Activity and stability of chemically modified Candida antarctica lipase B adsorbed on solid supports |
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Authors: | B C Koops E Papadimou H M Verheij A J Slotboom M R Egmond |
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Institution: | (1) Department of Enzymology and Protein Engineering, Centre for Biomembranes and Lipid Enzymology, Institute of Biomembranes, Utrecht University, P.O. Box 80054, 3508 TB Utrecht, The Netherlands e-mail: a.j.slotboom@chem.uu.nl Tel.: +31 30 2533178 Fax: +31 30 2522478, NL |
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Abstract: | The effect of various covalent chemical modifications on the transesterification activity and stability of adsorbed lipase
B from Candida antarctica (CALB) was studied in 2-butanone and o-xylene. CALB species modified with either polyethylene glycol 2000 monomethyl ether (MPEG), polyethylene glycol 300 mono-octyl
ether (OPEG) or n-octanol (OCT) were used in combination with a hydrophobic (Accurel) and a hydrophilic (Duolite) support. The thermostabilities
of adsorbed CALB in both solvents, and that of free CALB in o-xylene were not influenced by the modifications. In contrast, the thermostability of free CALB in 2-butanone decreased 2.5-fold
after MPEG modification and increased 1.5-fold after modification with OPEG and n-octanol, compared to that of native CALB. The activities of the native and modified CALB species were up to 9-fold higher
after adsorption onto Accurel than those of the corresponding free enzymes. Adsorption of these enzyme species onto Duolite
only resulted in a 2- to 3-fold increase in the activity of OPEG- and OCT-modified CALB. The modified CALB species adsorbed
onto Accurel show similar or up to 2-fold lower activities than do native adsorbed CALB species, while 1.5- to 6-fold higher
activities were found for modified CALB species adsorbed onto Duolite. We propose that hydrophobic modifiers induce conformational
changes of CALB during adsorption on a hydrophobic support whereas all three modifiers protect CALB from structural alterations
during adsorption onto a hydrophilic support.
Received: 18 March 1999 / Received revision: 21 June 1999 / Accepted: 27 June 1999 |
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